16 BULLETIN 859, U. S. DEPARTMENT OE AGRICULTURE. 
250 cubic-centimeter tared beaker and dried at 60° to 70° C. to 
apparent dryness, after which it was dried in vacuo at 80° C. until 
the loss between two successive weighings was negligible. For ash 
the residue was ground in a mortar, then placed in the vacuum oven 
over night and approximately one-half of the total sample used for 
the crude-ash determination. 
Acidity. — All acid determinations were made with fresh material. 
Two hundred grams of tomatoes were pulped and placed in a liter 
volumetric flask, made up to volume with cold distilled water, and 
toluol was added to prevent the growth of organisms. After stand- 
ing three days, 50 c. c. aliquots were titrated against approximately 
a tenth normal sodium-hydroxid solution (N/10 NaOH), using 
phenolphthalein as the indicator. No trouble was experienced in 
determining the end point. Separate determinations were made 
until the duplicates checked. In order to determine the effect of enzyms 
on acid content, a sample treated with boiling water was titrated 
three days later and the results compared with one using cold 
water. For the former, 200 grams of material required 14.28 c. c. 
N/10 NaOH, and for the same quantity of material employing cold 
water, 14.18 c. c. N/10 NaOH were required for neutralization. 
Free reducing substances. — One-tenth of the original alcoholic extract 
was evaporated nearly to dryness while the same part of the residue 
was being extracted on a filter paper with warm water (35° C). 
Very little reducing substance remained after extracting the original 
residue with alcohol, as described under " Sampling and preserva- 
tion," but the warm-water extraction was performed to insure the 
removal of final traces. The aqueous extract was combined with the 
residue from the alcoholic portion and filtered into a 250 c. c. volu- 
metric flask, after which the filter paper was thoroughly washed. 
One cubic centimeter of lead-acetate solution (a saturated solution 
of the normal salt) was added and the solution made up to volume 
at 20° C. The whole was filtered immediately and the excess of 
lead removed by adding approximately 0.5 gram of sodium oxalate. 
After standing a short time the mixture was filtered through dry 
filter paper and 10 c. c. of the clear solution used for the sugar deter- 
mination. The method used for determining reducing sugars was a 
combination of that of Bertrand (10), and that of Munson and 
Walker (33, 56). In this method the cuprous oxid is determined by 
titration, as in the Bertrand method, Fehling's solution and the 
time of heating are as specified by Munson and Walker. The Munson 
and Walker tables were used for the sugar equivalents. 
Total sugars. — Fifty cubic centimeters of the solution used for 
free reducing sugars were transferred to a 100 c. c. volumetric flask 
and 5 c. c. of HC1 (sp. gr., 1.19) added. The mixture was set aside 
over night and the flask made to volume at 20° C. the following morn- 
